Cut-out switch for electric motors



June 8, 1937. J, M NAUL 2,083,343

CUT-OUT SWITCH FOR ELECTRIC MOTORS Filed May 14, 1955 2 Sheets-Sheet 1La? l' fw @M W W June 8, 1937. J, M NAUL 2,083,343

CUT-OUT SWITCH FOR ELECTRIC MOTORS Filed May 14, 1955 2 Sheets-Sheet 2Patented June 8, 1937 UNITED sTAT-:s

PATENT OFFlC James M. Naul, Fanwood, N. J., assigner to The SingerManufacturing Company, Elizabeth, N. J., a corporation of New JerseyApplication May 14, 1935, Serial No. 21,355

2 Claims.

This invention relates to electric motors and more particularly toalternating current motors having stationary exciting windings whichrequire switching provisions in connection therewith to meet startingand running requirements of the windings. For example, there is a typeof single phase electric motor, known as a splitphase motor, having onits stator a running winding and a starting winding at an electricalangle to the running winding. When the motor is at rest both windingsare connected in parallel and are so designed that when connected to thepower line the currents flowing in the two windings are out of phase andproduce the rotating magnetic field necessary to start the motor. Afterthe motor has been started it is necessary to cut out or open thecircuit through the starting winding to prevent the latter from burningout, as it is normally designed to safely carry its starting current fora few seconds only.

The present invention has for an object to produce a centrifugalmotor-circuit-controlling switch of simple, durable and inexpensiveconstruction which will operate automatically and quickly to open andclose the motor-winding circuit controlled thereby and which will notflutter indecisively or chatter at any speed of the motor. Afurtherobject of the invention is to provide a switch of the classdescribed having minimum space requirements for its installation andoperation within the motor.

With the above and other objects in view, as will hereinafter appear,the invention comprises the devices, combinations and arrangements ofparts hereinafter set forth and illustrated in the accompanying drawingsof a preferred embodiment of the invention, from which the severalfeatures of the invention and the advantages attained thereby will bereadily understood by those skilled in the art.

In the accompanying drawings Fig. 1 is av section through one end of anelectric motor fitted with a switch embodying the invention, theswitch-contacts being closed as when the motor shaft is stationary. Fig.2 is a similar view of the switch with the contacts open as when themotor shaft is running at normal speed. Fig. 3 is a sectional view ofthe toggle-elements of the switch. Fig. 4 is a section on the line 4 4,Fig. l. Fig. 5 is a view of the switch contact elements. Fig. 6 is aperspective view of the switch. Fig. 7 is a perspective view of theswitch base and Figs. 8 and 9 are perspective views of certain leverelements of the switch.

In the specific embodiment of the invention illustrated, I representsthe casing and 2 one of the end-bonnets of a single-phase alternatingcurrent electric motor having a stator 3 and a rotor 4 carried by themotor-shaft 5 journaled at one end in the bearing 6 in the end-bonnet 2.The stator is energized by the usual running and starting windingsindicated collectively at 1, the latter of which requires to beopen-circuited as the motor comes up to speed.

Mounted on pillars 8 projecting inwardly from the motor end-bonnet 2 isthe sheet-metal switch-base 9 having riveted thereto a sheet of stiffinsulating material I upon which are mounted in spaced relation thestationary terminal plates Il carrying the contacts II and connected inthe starting winding circuit by the leads I2, Fig. 6.

The switch base 9 has bent up from the plane thereof a pairv of spacedlower ears I3 and a pair of V spaced upper ears I4 which ears are formedwith opposed fulcrum notches I5, I', Fig. 7. 'I'he switch base 9 has acentral aperture I6 to clear the motor shaft 5.

Resting in the fulcrum notches I5 in the lower pair of ears I3 are thefulcrum edges I'I, defined by corner notches at the ends of the baseedge I8 of a sheet-metal toggle-actuating lever I9 having an aperture toclear the motor-shaft 5. The lever I9 is formed at its upper end with anotch 2| in which is rockably seated the lower notched end of an endwiseexpansible togglethrust member 22. The lever I9 is formed adjacent thenotch 2| with an apertured ear 23 loosely embracing the stationaryheaded guidepin 24 which is ilxed to the base 9. spring 25 surrounds thepin 24 between the ear 23 and the base!! and yieldingly urges the ear 23toward the head of the pin 24 which functions as a stop. The lever I9 isformed with the diametrically opposed humps 26 which are engaged attimes by the centrifugal or speed-responsive mechanism to be described.

Seated in the notches I5 of the upper pair of ears I4 are the fulcrumedges 21 at the ends of the arched or U-shaped toggle-operated lever 28to one end of which is riveted a piece of stiff insulating material 29loosely carrying the bridging contact button 30 which may tilt slightlyrelative to its supporting arm 29 and which, at times, engages thespaced stationary contacts II. The toggle-operated lever 28 is formedwith a centrally disposed notch 3| in which is rock- 'ably seated thenotched upper end of the expansible toggle-thrust-member 22 which remov-A coiled ably retains bothievers il and Il seated in their respectivefulcrum notches Il. Il'.

As shown in Fig. 8. the toggle-thrust-member I! comprises two telescopedand headed rods Il' surrounded by a coiled spring 22".

The edge of the notch 2i in the lever I. is disposed above a lineconnecting the notches Il' in the upper ears il, so that movement of thelever Il in either direction about its fulcrum edges I1 will nrstcompress the toggle-thrustslement 22 until such element crosses theplane of the toggle-operated lever Il. whereupon the lever 2l will besuddenly and decisively shifted to its opposite extreme position aboutits fulcrum edges I1. It will be understood that, in one extremeposition oi' the lever 2l. the movable contact button 3l engages thestationary contacts Il and closes the circuit through the startingwinding o! the motor. In the other extreme position of the lever 2l thebutton 8l is widely separated from the stationary contacts Ii.

The speed-responsive mechanism may comprise a base 32 fast on themotor-shaft and formed with side cheek pieces having ears u supportingthe parallel pivot-pins Il for the weighted levers Il having inwardlyextending arms l1 entering the groove 3l in the collar 3l slldable onthe motor-shaft. The collar 3| carries at one end a fiber head l0 which,at times, engages the humps 2l of the toggle-lever i9. A spring 4I isdisposed between the base 32 and the collar l0. This spring is strongenough to overpower the spring 2B and force the lever il to the positionshown in Figs. l and 6 as the motor slows down. Coiled springs l2 arestretched between the arms 4I. I3 of the weighted levers Il and resistthe centrifugal expansive forces set up in the weighted levers.

When the motor is started and the speed of the shaft l increases beyonda predetermined value, the centrifugal forces set up in the weightedlevers IC overcome the resistance of the springs 4i and 42 and thecollar Il ls withdrawn from engagement with the leverll which is shiftedby the spring Il to the extreme posi-l tion shown in Fig. 2.

The foregoing specincation ls to be read in an illustrative sense andnot in limitation of the invention; it being understood that variousmodifications may be made in the details of construction and relativearrangements of parts shown and described .within the spirit and scopeof the invention.

Having thus set forth the nature of the lnvention. what I claim hereinisz- 1. In a toggle switch, a base-plate adapted for mountingat theinner side of a motosl end-bonnet, a toggle-lever fulcrumed at one endon said base and having a clearance aperture for the motor-shaft, aU-shaped toggle-operated lever fulcrumed at the ends of' its legs onsaid base, an endwise spring expansible toggle-thrustmember rockablyreacting at its opposite ends against said toggle-lever and the centralportion of said U-shaped toggle-operated lever, a movable contactcarried by said toggle-operated lever, and a stationary contact carriedby said base.

2. In a snap-switch. the combination with a flat base having two pairsof notched ears projecting from the same side of and standing at anangle to the plane of said base. the notches of each pair of earsopening in a direction toward the other pair of ears. a flattoggle-actuating lever fulcrumed in the notches of one pair of ears, aat-toggle-actuated lever fulcruxned in the notches of the other pair ofears, a springexpansible toggle-thrust-member between and rockablyconnected to each of said levers, and a movable contact carried by saidtoggle-actuated lever.

Jaime M. RAUL

